Blood transfer mechanism



Jam. 20, 1953- P. F. sALlsBURY 2,625,933

BLOOD TRANSFER MECHANISM Filed Jan. l0, 1949 3 Sheets-Sheet 1 1N V EN TUR.

Pm EM f4 Trek/VEK- Jan. 20, 1953 P. F. sALlsBuRY 2,625,933

BLOOD TRANSFER MECHANISM Filed Jan. 1o, 1949 5 sheets-sheet 2 f-A TTaeA/E V- Jan. 20, 1953 P. F. sALlsBURY 2,625,933

BLOOD TRANSFER MECHANISM Filed Jan. 10, 1949 3 Sheets-Sheet I5 25A zoll 20A 26h l l j I /o/, /o/as@ SMC] 99 /00 /00 INVENTOR.

Patented Jan. 20, 1953 UNITED STATES PATENT AGFFCE BLOOD TRANSFER MECHANISM Peter F. Salisbury, Beverly Hills, Calif.

Application May 10, 1949, Serial No. 92,310

11 Claims.

l This invention relates to that branch of the medical art in Which all or a large part of the -blood supplies of two persons are interchanged, and has as a general object to provide an apparatus for effecting and for metering the interchange of blood between a patient and a donor. The invention is directed to the general type of apparatus disclosed in my earlier application Serial No. 70,013, filed January 10, 1949, of which the present application is in part a continuation. -A particular object is to provide for equalizing the flow in both directions.

Another object is to provide a blood metering apparatus of a high degree of accuracy.

Another object is to provide a blood interchange and/or metering apparatus including -means for automatically metering the blood being interchanged and for automatically shifting from one cycle of operation to another under the control of a metering mechanism.

A further object is to provide a novel blood interchange and/or metering apparatus including novel control mechanism, sensitive to the rise and fall of blood level in a metering chamber, for automatically controlling'a cycling action in the apparatus.

A further object of the invention is to provide a blood interchange and/or metering apparatus having electric motor driven means for automatically reversing the cycle of operation thereof in response to the rise and fall of blood level in a metering chamber.

Another object is vto provide a blood interchange and/or metering apparatus having electric motor driven means for pumping blood from a patient or donor into a metering chamber, with ymeans responsive automatically to upper and lower liquid level limits in said chamber, for recurrently arresting the pumping action, reversing the movement of the blood and evacuating the chamber, and then again reversing the movement and starting the pumping action anew for another cycle of operation.

Another object is to provide such an apparatus in which the subjection of the blood to pumping action is kept at a minimum so as to minimize the destructive action of the pumping on blood cells. To this end, the invention contemplates the utilization of gravity, either alone or assisted Iby the gentle steady pressure of a fluid in a plenum chamber communicating with a metering chamber, for evacuating the latter after it has been iilledby the pumping action.

--In one of its specific aspects, the invention contemplates a pumping arrangement in which a fluid (e. g., air or an inert gas or liquid) above (Cl. 12S- 214) `blood from the metering chamber.

the blood in a metering chamber is alternately subjected to suction and compression so as to alternately draw the blood into and expel the Such an arrangement has the advantage of avoiding direct contact of the blood cells with moving mechanical parts of a pump.

A further object of the invention is to provide novel liquid level sensitive control means for controlling the operation of an apparatus as specified above. Such control means may take the form of photosensitive means, or electrostatic means, or electric switch means utilizing the blood itself as a portion of the control circuit, and the invention aims to utilize any of these several circuit control mechanisms for controlling the blood interchange apparatus.

In another of its specific aspects, the invention contemplates an arrangement in which the lling and evacuation of a metering chamber is co-ntrolled by a pair of controls responsive respectively to minimum and maximum weights of the chamber and contents (determined by emptying and filling of the chamber respectively).

Other objects will become apparent in the ensuing specications and drawings in which:

Fig. 1 is a schematic view of a modified form of control device of the general type shown in Fig. 8;

Fig. 2 is a detail vieW of a modified form oi circuit controller;

Fig. 3 is a detail view of another modified form of circuit controller;

Fig. 4 is a detail View of another modiied form of circuit controller;

Fig. 5 is a schematic View of a blood transfer apparatus embodying one form of the invention;

Fig. 6 is a schematic View of a blood transfer apparatus embodying a modied form of the invention;

Fig. 'l is a schematic view of a modiiied form of a metering chamber; and

Fig. 8 is a schematic view of a blood transfer apparatus embodying another modied form of the invention.

General features of the intention In general the invention provides means, such as vessels l0, I9' of Fig. 5 for defining a pair of metering chambers in which blood is metered as it is cross-transferred from the body of a donor, indicated schematically at A to the body of a patient, indicated at B, and from the latter to the donor. The invention also provides a system of flow conduits i3, I3 and I4, ld'; a corresponding set of valves 23, 23V and 26, 24 for controlling 3 l-flow therethrough in a manner to effect the -result referred to above; and suitable means, such as pumps SI1, 60 (Fig. 5) for inducing the flows of blood through the metering chambers.

Valves 23, 24 etc., may be of any known type, suitably selected for use in a system of the type contemplated by the invention. Preferably, the valves are of the general type commonly employed in apparatus (such as hot water bottle apparatus) in which a fluid conducting nexible =tube has a short section thereof functioning as a valve under the action of means for pinching the tube so as to collapse it, thereby shutting off yflow therethrough. The pinching means comprises any suitable pair of opposed jaw members one of which, in the valve contemplated by the present invention, is actuated by Va solenoid. y d

Metering chambers Iii, Iii' (as well as all other parts of the apparatus with which the blood makes `direct contact) are constructed from inert material, such as, for example, polyethylene or other inert synthetic plastic material, or of glass or Vmetal coated with an inert, non-wettable lm (such as a silicone, 'or other non-wettable coagulation retarding material). A silicone coatingr is preferred, since it possesses a high degree of coagulation retarding properties (is 'waterrepellent or non-wettable, which retards coagulation because the blood cells have little opportunity to become static by adhering to the non- `wetting surface).

Blood withdrawing and injection catheters are indicated at II, II', I2 and I2 respectively. Such catheters may be combined in a single instrument as disclosed in my pending application above referred to. Catheters II and I 2', in the apparatus of Fig. 5, are connected through conduits Iii and I3 and a i`union I5 to the bottom of chamber I8. Catheters II and I2 are connected through conduits I-t and I3 and a =Tunion I5 to the bottom of chamber Iii'. Pumps '653, Si) are actuated in opposed phase by ymeans which will be described hereinafter, to cause a flow into'one metering chamber while the other is being emptied, and vice versa.

The blood is metered by controlling its flow -into and out of the chambers I0, I9' so that such flow will be arrested at upper and lower limits of the blood levels in the respective chambers. Such arresting of ow is brought about through the use of the above mentioned flow control valves actuated by controls responsive to such upper and lower level limits. The liquid level responsive controls may comprise pairs of photoelectric cells 2i?, 2l and 26', 2| for the respective chambers Iii and I il'. The photocells 2i and ZI may be arranged in communication with transparent `portions of the connections between T-unions I5, I and the chambers Iii, Ii; and the photocells 22, 29 may be arranged in communication iwith transparent portions of vents 22, extending -upwardly from the tops of the respective chambers. Light beams (not shown) may be arranged to shine through the T-unions I5, I5' and vents 22 when not cut off by the columns of blood standing in these connections and vents, and, consequently, the respective photocells will be energized when the liquid columns behind them drop below the light beams to which they are respectively responsive.

The photocells 20, Ai. I, 28', 2 I control the operation of respective valves 23, '24', 23', 2li which lin turn control flow through the conduits I3, Iii', I3', I4 respectively. Where the valves 23, 2d', 23', 24 are of the constrictor type, the conduits 4 II3, I, I3', I4 will be of a resilient, readily collapsible tubing of suitable plastic or rubber material, preferably coated internally with an inert, non-wettable llm such as that referred to above.

The invention utilizes a suitable system of electrical controls for alternately opening and closing the valves so as to produce the desired flow. For example, valves 23 and 2d may be closed while valves 24 and 23' are open, whereby blood may flow from chamber It through conduit I3 into body B while blood from body B flows through conduit I4 into chamber IIB. In the system shown, the ow to and from body A will be cut voif during this half-cycle of operation.

As an example of one set of electrical controls that may be utilized, I have shown a plurality of relays 25, 26', 25', 2t responsive respectively to photocells 2B, 2I, 2t', 2|' respectively. To this end, the energizing coils fof the respective relays may be connected through conductors 2l to the respective photocells and suitably connected to a source of relay energizing electric power which is indicated at E. Each relay 25, 25, etc., has a contact head di cooperable with suitable contacts to complete a circuit through a. conductor 29 and a solenoid energizing coil 3 to another source of power which is indicated by the reference character F. Coils il constitute the energizing coils of valve operating solenoids 3-I, 32, 3i', 32V' for operating valves 23, 2li, 23'-, 2i' respectively. Each of the solenoids 3i, 32, 3i', 32' includes a holding coil 33 for maintaining the energization of the respective relay until cut on (e. g., by the opening of a respective limit switch 35A or `315 rin he form of theinvention shown in Fig. 5). Holding coils 33 may ybe immediately controlled by conventional solenoid operated holding coil switches 313 each having a movable contact which is operated by the respective solenoid armature, whereby a holding coil will be energized coincidentally with the energization of a respective energizing coil Sil.

As each of the sol'enoids 32, 3i' isenergized, a holding circuit will be 'established from power source F through a respective holding coil 3-3, a `conductor (4t for solenoids 3i and 32', -'I for solenoids 3 I and v32') toa respective holding coil switch 34.

Each limit switch 35, 35, may include a fixed contact and a swinging armY spring-urged normally into engagement with the Xed contact` and adapted to be moved outof, engagement therewith by a walking beam Gt forming part of the pump actuating mechanism.

Relays 25 and 25' a-reof theself-closing typeopen when energized, closed when cle-energized. Relays 25 and 2S' are `of the self-opening Vtype-- closed vwhen energized and open when gie-energized. Solenoids-L'i', 32, 32' are all of-a selfopening type, closing valves'23, 2li, 233213' when energized, opening the valves when de-energized. For example, the valve-solenoid unit may be spring urged to open position. Photocells 20, 2t' become cle-energized when 'the liquid -level in chambers IG, I-il' rises 4,to maximum height, thereby closing Yrelays 25, 25. Photocells 2I, 2l' become energized when'the liquid levels in chambers I i), I 0 drop to minimum levels, thereby closing relays 26, 2S.

Modified forms or-liquid Zcel responsive controls Fig. 2 illustrates la modihedcontrol system'embodying electrodes 20u, 2Iafof inert metal such asplatinumsealed into thev'e'n't '22o andu'ni'on lia respectively and adapted to establish respec- 'tive circuits to relays 25a, 26a when contacted by the -upper level of the body of blood in chamber Illa.v A ground connection G may also embody an electrode sealed into the bottom of union I5a, below the level ofrboth electrodes 20arand 2Ia. Circuits are established from ground connection G through the blood to contacts 20a and 2IaI respectively. This form of circuit controller is not as desirable as the photocell type shown in Fig. 1, for the reason'that some electrolysis of blood may take place.

In Fig. 3 I have shown another modication of the control units. In this case, stems 20hA and 2Ib of relays 25h, 2Gb respectively are actuated mechanically by a oat 48 slidably mounted in a guid-e tube 49 the respective endsof which communicate with union I5b and vent 22hV respectively. Tube 49 is perforated to provide communication with chamber Ib. The stems 20D, 2 Ib may, for example, be slidably mounted in bearings in the vent 22h and union I5b respectively, for free sliding movement in response to the camming engagement of inclined end portions of float 48 against the yielding resistance of springs 50 that are operative to return the movable relay members to normal positions when disengagedby float 48.

Fig. 4 illustrates a stillV further modication of the circuit control units, embodyingl capacitor elements 20c, 2 Ic embracing vent 22e` and union I5c respectively. Capacitor elements 20c, 2 Ic are connected by conductors 21o to conventional electronic relays 25e, 26o adapted, in response to change in the dielectric condition of units 20c, 2Ic to con-trol the operation of the valve solenoids. Change in dielectric condition of units 2llc, 2 Ic will occur when columns of blood enter or leave the passages within vent 22e and union I5c.

Either of the circuit control arrangements shown in Figs. 2, 3 or 4 may be utilized for triggering the operation of solenoids 3l, 32, 3| and 32' of Fig. l, or the corresponding solenoids of the modications of the general apparatus shown in Fig. 5 et seq.

Suction-compression type apparatus In Fig. 5 is illustrated a form of the invention in which the metering chambers III, I0' are supported in xed positions and in which blood is alternately drawn into the chambers and expelled therefrom by suction-compression units 60. Such suction-compression units may each include a rigid walled housing 6I closed on one side by a exible diaphragm 62 of material having the characteristics of soft rubber. The diaphragm 62 is sealed to the open'mouth of the housing BI so that no leakage of air past the diaphragm will occur. Each housing 6I communicates with a corresponding chamber I0, I0' through a passage 22. Each diaphragm 62 is attached to a piston 63 carried by a piston rod 64 slidably mounted in a bearing 65. The respective pistons are reciprocated with opposed timing so that when one diaphragm is moving inwardly the other will be moving outwardlyV and vice versa. This may be accomplished by any suitable means such as for example the walking beam 66, oscillated about a fulcrum pivot 61 by a pitman 68 connected to it by'sui'table linkage 69,7with an electric motor I0 driving the ptman 68 through suitable reduction gearing 'II, all shown schematically.

Diaphragms 62 and housings '6I *cooperate` to deilne chambers I2 in which the diaphragms will alternately vexert suction and compression against the air therein, which suction and compression stages .are transmitted to chambers I0, III' to draw blood into or expel blood from such chambers f The systemincludes transfer conduits I3, I4, I3', I4', controlled by va1ves'23, 24, 23', 24' which in turn are operated by solenoids 3I, 32, 3I.l 32' under the control of relays 25, 26, 25', 2B' respectively as previously described. Solenoid holding circuits are controlled by limit switches 35 and 35', which are operated by the respective extremities of walking beam 65 as indicated.

It is contemplated that the motor 'I0 may be operated continuously at a speed adjusted to the requirements ofthe blood transfer operation that is being performed; To provide for some adjustment, the motor 'III may be a variable speed motor. The diaphragms 62 may be of sumcient ilexibility to permit of valves 23, 24, 23', 24 being at least occasionally closed somewhat prior to the end of the strokes of pistons 63, so that the fluid iiow Will be controlled directly in accordance with the valve action rather than in accordance with the complete strokes of the pistons 63. This makes it possible to obtain the desired accuracy of metering action, while allowing the diaphragms to operate continuously at a uniform rhythm. Any substantial movementof a piston 63 either inwardly or outwardly after the closing of a valve has arrested liquid iiow into or out of its corresponding chamber I0, III', may be compensated by a certain degree of collapsing or expanding of the diaphragms 62 radially so as to avoid any substantial increase in the compression or rarefaction of the air within chambers 12.

Operation of suction-compression type apparatus With the switch 13 closed and the motor 10 operating, reciprocating movement will be transmitted to pistons 63 by linkage S8, 1I, 66 and 64, slowly reciprocating the pistons 63 in alternating, opposed rhythm, one piston moving inwardly while the other piston moves outwardly and vice versa. With the parts moving as indicated by the arrows in Fig. 5, atmosphere in the left chamber I will be subjected to compression, expelling donors blood through conduit I3' into patient B, while patients blood is withdrawn through conduit I4 into right hand chamber III by suction applied to this chamber by the upward movement of right hand diaphragm 62. When the rising liquid level has passed photocell 20', relay 25' will be de-energized and thereby closed, establishing a circuit to-solenoid 30 of valve 23', interrupting the flow of blood through conduit I4'. When the sinking liquid level in left hand chamber I0 uncovers photocell 2I, relay 26' will be energized and thereby closed, establishing a circuit through solenoid 32' closing valve 24' and arresting ow through conduit I3' into patient B. All four valves will then remain closed until the walking beam 66 completes its stroke, whereupon limit switch 35 will be opened, releasing holding coils 33 of solenoids 3l and 32' and allowing valves 23 and 24' to open. Left hand diaphragm 62 will now be moving outwardly and right hand diaphragm inwardly causing donors blood to be drawn into left hand chamber I 0 through conduit I4 and patients blood to be expelled from right hand chamber I0' through conduit I3 into donor. When the rising liquid level in left hand chamber II) passes photocell 20, relay 25 will be deenergized, and thereby closed, energizing solenoid 3| and closing valve 23. When falling liquid level in; right hand chamber |07 uncovers photocell 2.1!. relay.` 2.5. will be, energized, and thereby closed, energizing solenoid 32 and closing valve 24. Thisv completesa cycleof operation and, with the pis-` tons 63 again moving in the directions indicated by the arrows, the. liquid levels in chambers I0, It will shortly reach the positions shownV in Fig. 5, thus completing one cycle of operation.

Plenum chamber type apparatus Fig. d illustrates a possible modificationof the now inducing` arrangement, in which there are interposedbetween the respective 'lf-unions |5e and chambers It, le' pumps 8|, 8|" each having tsoutlet connected to a union- Ie andv its inlet connected to one `ofthe return conduits |4 lil'. Vents; 252 communicate with housings B3, closed byv distensible daphragms Se, 3,4" to denne therewithjplenum chambers PLP. The diaphragme. t4, 84," are stretched under tension so as to be constrained toward assuming dat positions. The pumps 8|, 8|" are` operative to induce ilow into the respective chambers it, it" alternately from the respective bodies A and B, under the control of valves 23, 23"', 24, 2d. Pumps 8|, Si are driven by electric motors 85, Se each of which is adapted to be energizedcoincidentally with openingofjla pair orvaglves 23, 24 (or 2li', 23'). For example, motor y235I will be energized upon the simultaneous opening or valves 23 vand 24.-, and thesimultaneous opening of 'these two valves will follow immediately upontheV consecutive successiye closing oi'bothofvalves 23' and 2e' as described detail underthene-ict subheading hereof. i

De-energization of ak pump motor 85 (or 85') in Aorder to arrest a pumping stage,l is effected simultaneously with the closing of a valve 23 (or 23") which inturn; occurs when the; liduid level inV a chamber V|16 (or it!) reaches; maximum height.

The contrclsgforlvalves 23,213, 23', 2t" aresubstanti'a'lly the same as. in the other form of the invention, liquid level responsive controls 2i), 2G', 21,2] being; connected through conductors 2l to energizing; coils ofrelays 2te, 25e", 26a and 2 Se respectively; and ,being responsive to liquid level movements so `as, to close the respective contact heads 231- oaiv relays 25e, etc., against their cooperating contacts in responseto thearrival of liquid levels at the maximum and minimum positions respectively. Each such closing of a contact head` 23 against its contacts will, through aLconductor 29, energize la respective solenoid coil 3f)l so as'to close a respective valve- 23, 23', 223 or-Zt' as the case may be. Each valve, when thus closed,v will remain closed, by operation ofY holdingk coil 33 which becomes energized through a holding eircuit including asolenoid operated switch 343.

The solenoid holding circuits areasV follows: Contact head-s il ofrelays 25e-and 26e' are connectedin parallel by conduct-ors 515e and 41e' to solenoid operated holding coil contr-,ol switches 3i! of relaysill and 32' respectively. Similarly, contact heads il of relays 25e and 26e, when they engage 'their ,cooperating contacts, will establish holding circuits thro-ugh conductors 46c' and Ille to solenoid holding coil control switches 3.4 of solenoids'Sfia-nd 32j. In eachrcase the two relay contactfheads il are inV paralleli so that both centacitgheadsll must disengage their cooperating contactsn ordergtol open `their respective holding coil circuits.

Motors 85, 85' areenergized through relays y86.-,4 86.k which are undcrithe dual control ofi') i the valve opening circuits described immediately above, and- (b) the contact heads28 of relays 25e, 25e. Each relayI 86, 86' includes` a contact head- 8l and cooperating contacts adapted, when the relay is 4de-energized, to establish a circuit through a conductor 88 to a, corresponding motor winding 39 (or 39'). Energizing coil 89 of relay 86 (or 86') is connected through conductor 29 to the contacts which cooperate with head 28 of relay 25er (or 25e) whereby, when liquid level of chamber It (or |0) reaches the upper limit, and relay 25e (or 25e') is lconsequently de--energizedy closing contact head 28 against vits contacts to close valve 23 (or 23'), relay 86 @or 86') will coincidentally be energized to withdraw contact head 81 from its cooperating contacts, thereby breakingv the motor circuit of the pump 81| (or 8V) thus arresting the rise ofY liquid in the lled chamber.

Each of the relays y86, 8,5' includes a holding coil 90- whi'ch is energized coincidentally with energizing coil til through a holding coi-l switch 9| thernovablecontact of which moves in unison withhead 8i, closing when head 8-7 opensuestablishing a holding circuit through a conductor 92 to conductor ile (or ille'). Thus the holding circuit of relay. 35 is in parallelv with the holding circuits of relays 3| and 32 and the holding circuit ofrelay 8e' is in parallel with the holding circuits ofv relays 3|' and 32'. Consequently, the startingA of motor 35.(or will be coincident with the opening or Valves 23 and 24 (or 23 and 24').

Operation of plenum chamber type apparatus Fig. 6 illustrates a stage. of operation j-ust preceding the iilling of chamber it' and the emptying of chamber It'. The arrows indicate the flow o-f patients blood through conduit I4', pump 8|' and union |5e into chamber It' and the outflow of donors blood from chamber l0 through union I5@ and conduit I3 int-o patient B: TheV latter flow is a gravity Iiow, the chambers It and It being elevated above the level of the patient and donor sufficiently to provide for gravity evacuation of the chambers.

When the liquid level in chamber lil' reaches the upper limit, photocell 20' will be covered and relay 25e' will be cle-energized, resulting in: (a) clos-ing of relay 25e at headY 28, simultaneously energizing relay 3|' to-close.- valve 23' and energizing relay 8e' to open thesame at head El, de-

ener-gizing motor 85', stopping pum-p 8| and ar.-`

resting the rise of liquid level in chamber ilf; (b) opening relay 25e at head Allr so as to open one. branch of the holding circuit for relays 3|, 32 and 8S (conditioning these relays for operation when the-other branch of this holding circuit is opened).

When liquid leve-l in chamber drops tothe lowerl limit (which may occur either before or afterthe reaching of the upper limit of liquid level in chamberA HV) photocell 2| will be uncovered, energizing relaye and resulting in (a) closings-of'relay` 26e athead` 23 so as to energize solenoid 32' and close valve 213-' t-o arrest the outflow. of liquid from chamber It; and (b) opening relay 26e at head 4| so as to open the other branchY of theholding circuits for solenoids 3| and32 and relay 8S and degenergize these three instruments, resultingin the coincidental openingof valves 23v and 24 vand thestarting of motor B5 to operatepumpfS This completes thefchangeeover from one half cycle-ofoperation to another;- and the Y operation` human blood.

will proceed immediately with a new half cycle in which donors blood will be pumped through now open valve 23 and conduit I4, pump 8| and union |e into chamber I0, While patients blood will be discharged by gravity from chamber lil through union |5e' and conduit |3 into the donor. Valves 23' and 24' having been closed consecutively, as described above, will remain closed through the operation of holding coils 33, energized by the closing of their control switches 34. Thus the closed positions of these valves will remain unaffected by either (a) the re-energization of relay 2Ee' occurring shortlyafter the beginning of the new half cycle, asv the result of liquid level in chamber I0 dropping away from its upper level and uncovering photocell or (b) the de-energization of relay e occurring likewise shortly after the beginning of the new half cycle as the result of liquid level again covering photocell 2| as donors blood is pumped into Vchamber VI 0.

, In the new half cycle, all valves and relays will remain in the positions last described above until the liquid level'in chamber I0 reaches the upper limit; (or until the liquid level in chamber l0 reaches the lower limit, whichever occurs first).

will be uncovered, energizing relay'ZBe and ef- Iecting: (la) opening of relay 26e at head 4|, opening the other branch of holding circuit to 4solenoids 3|' and 32 and relay 86 thus de-energizing the holding coils of these instruments and releasing each of them for movement to their .positions in which: (l) valves 23 and 2d' return to their open positions shown in the drawing and (2)` head 81 of relay 86 re-engages its contacts to re-establish the circuit to motor 85', starting the operation of pump 8|'; and (b) closing of relay 26e at head 28, re-energizing relay 32 and closing valve 24. This completes the second half of a complete cycle of operation, and starts a new cycle of operation in which patients blood will be pumped into chamber I0 and donors blood evacuated from chamber l0 and delivered to the patient, all as indicated by the arrows in Fig. 6.

This form of the invention differs from the previously described form in the following particulars: (a) Evacuationof the chambers ill and l0' is brought about by the pressure o f gas in the ,plenum chambers 85 and 85', responding to the pressure of distended diaphragms 8A, B15. Chambers P, P' may be filled with air or with an inert gas which has a minimum absorption in (b) Cycling operation is attained without the utilization of mechanically tripped limit switches, the changes of cycle being effected ventirely by electrically operated relays responsive solely to the movement of the blo-od to its respec- :tive limits in chambers l0 and I0.

Apparatus of Eig. 7

`Instead of a gaseous atmosphere above the .'blood in the metering chambers, an inert liquid,

such as mineral oil, may be used. In such a .-case, the arrangement of Fig. 6 could be modified :to include a storage chamber 85j above each metering chamber,

communicating with the metering chamber through a passage 22f and in turn communicating with atmosphere through a vent 22g, as shown in Fig. 7. In the arrangements of Figs. 5 ande, the chambers it, P, P' respectively could be lled with an inert liquid without otherwise modifying the apparatus. Such an arrangement would have the advantage of avoiding the absorption of gas into the blood being pumped.

The system, modii'led in accordance with Fig. 7. would further distinguish from the other forms of the invention in that ilow from the metering chamber would be a gravity ilow. In such modined arrangement inert liquid IB would float on the body of blood and would rise and fall therewith.

Weight responsive control type apparatus Fig. 8 illustrates schematically how metering chambers ith may be controlled by the weight of blood in the chambers. Chambers Illh may be suspended by any suitable counterbalancing arrangement utilizing weights or springs for coun terbalancing the chambers in such a manner that when empty, they will exert upward pressure against pressure sensitive control elements such as the strain gages which are indicated schematically at 23h, and when iilled, they will exert pressure downwardly against pressure Ksensitive controls such as the strain gages 2 Ih.

As an example of one arrangement for counterbalancing chambers wh, Fig. 8 illustrates the mounting of the chambers mh' on levers 99, fulcrumed on nxed Isupports vat It, and having c-ounterweights Iii adapted to establish an upward load on chambers ith, when the latter are empty, and to be overbalanced when the chambers are filled. The counterbalancing can be so adjusted to the strain gages 26h and 2|h that one circuit will be established when the metering chamber is emptied and another circuit will be established when the metering chamber is filled. These circuits may be triggered through relays 25h, 25h', 26h, 26h', which may be the same as relays 25e, 25e', 26e, 26e', of Fig. 6. The remainder of the apparatus and the electrical control circuit, may be the same as that shown in Fig. 6, and consequently has not been illustrated in detail in Fig. 8.

Instead of the strain gages 2 Ih, other pressure or weight sensitive devices such as a weighing device having a pointer equipped with an electric contact, can be utilized. Also, instead of utilizing two of the pressure responsive controls for each chamber, it would be possible toutilize a weighing device equipped with a pointer operating between a pair of contacts, with-the pointer playing between the two contacts in accordance with the `degree of filling lor emptying of the chamber, engaging one contact when the chamber is empty and engaging the other contact when the chamber is full. ASuch a; control in eiiect vwould be a combination of the ytwo controls of the previous forms of the invention, the one contact corresponding to one control and the other contact corresponding to the other control. A schematic illustration of such a two-way control device is shown in Fig. -1, the lnumeral indicating a weighing device having awmovable part 99 adapted to be attacheddtoor supportthe metering chamber |071., having a base 91 for engagement with a xed support,Y andhaving a pressure responsive pointer 98 playing between contacts 2th and 2m and responsive to pressure l 1 against part 99. The pointer 98 may be equipped with corresponding contacts h and 2lb', cooperable with contacts 20h and 2111 to provide two separate switching units, one adapted to close when the chamber Ih is emptied and the other adapted to close when the chamber I 0h is full.

General features It is to be noted that, in each of the forms of the invention shown, it is impossible for a new cycle or half cycle of operation to commence until the previous half Cycle has been completed. The reversal of iiow in each chamber occurs exactly at the upper and lower liquid level limits and consequently an accurate metering action is obtained, exactly the same amount of blood being drawn into each chamber in each half cycle operation. Consequently, the amount of blood transferred fr-om the patient to the donor will be exactly the same as the amount of blood transferred from the donor to the patient, and the total quantity of blood transferred will be accurately recorded by recording (either manually or through automatic recording instruments) the number of cycles of operation.

It is possible to use the apparatus not only for blood interchange between a patient and donor, but also for an operation in which blood is Withdrawn from a patient while blood or serum coming from a storage chamber(instead of directly from the body of a donor) is injected into the patient. In such an operation, conduits I3 and le may be connected, one to a storage vessel from which blood may be drawn into chamber IB, and the other to a receptacle into which the patients blood may be discharged. After a suitable sterilizing operation, the patients blood could then be either stored for any future use for which it might be suitable, or it could be returned to the body of the patient in a subsequent cycle of the same general operation in which it is withdrawn. Similarly, the apparatus could be used for withdrawing blood from a donor and injecting it into a storage container for storage and future use, while simultaneously injecting into the donors veins an inert saline'solution to re place the liquid content of the withdrawn blood. In each of such alternative operations it would of course be possible to utilize the metering function of the apparatus to record accurately the quantity of blood taken from a storage vessel and the quantity of Yblood delivered into a storage receptacle, as well as recording accurately the amount of patients blood replaced by storage blood or serum; or, in the alternative, the amount of donors blood replaced by storage blood or a saline solution.

I claim:

l. In a blood transfer apparatus, in combination with a pair of catheter means for insertion into blood channels of respective bodies, each of said catheter means including a withdrawal catheter and an injection catheter; a pair of metering chambers each having restricted passages communicating'respectively with its upper and lower extremities, conduits branching from each of the lower passages and communicating with one each of said inlet and withdrawal catheters, means for inducing -outfiow from one of said chambers and inow into the other of saidchambers and, alternately, Vinducing inflow into said one chamber and outflow from said other chamber, and means responsive to changein blood level in said upper and lower passages respectively for directing said outiiows Yalternately to one Cil 12 and then the other of said injection catheters and for directing said inflows alternately from one and then from the other of said withdrawal catheters.

2. Apparatus as dened in claim 1, wherein said flow inducing means comprises means for alternately applying suction and compression to the upper regions of the respective chambers.

3. Apparatus as defined in claim 1, wherein said flow inducing means comprises means to pump the blood into the respective chambers, and means yieldingly opposing the inflow into each chamber and operative, when the .operation of the pumping means is arrested, to expel the blood from the chamber, said yieldingly opposing means compri-sing means defining a plenum chamber communicating with the upper passage of a respective metering chamber, said last named means including a flexible, elastic diaphragm forming one wall of the plenum chamber and adapted to be distended by the expelling of fluid from the metering chamber into the Vplenum chamber as the metering chamber is iilled with blood, said diaphragm acting to yieldingly im pose pressure upon the plenum chamber and thus upon the metering chamber to expel the blood from the meteringchamber in the outow stage of operation oi the metering chamber.

4. Apparatus as defined in claim 1, wherein said blood level responsive means comprises photocells communicating with the respective passages so as to be responsive to activating light beams when passages are empty and to be de-'energizeo when vblood columns llsaid passages.

5. Apparatus as donned in claim 1, wherein said blood level responsive means comprises capacitors embracing the respective passages and responsive to dielectric condition changes resulting from the movement of blood columns into and out of said passages.

6. Apparatus as defined in claim 1, wherein said blood level responsive means comprises'a pair of controls responsive respectively to the weights of respective metering chambers when empty and when full of blood.

7. In a blood Ytransfer apparatus, in combination with a pair of catheter means for insertion into blood channels of respective bodies, each of said catheter means including a withdrawal device and an injection device; a pair of metering chambers; a pair of conduits for establishing communication with the bottom of each metering chamber and with one each of said inlet and withdrawal catheter devices, said conduits functioning for conducting outflow from one of said chambers and inflow into the other of said chambers, and, alternately conducting iniow into said one chamber and outow from said other chamber, and valvemeans responsive to change in blood level in said chambers at upper and lower liquid level limits therein, for establishing, in one half cycle of operation of the apparatus, through two of said conduits, consisting in one conduit of each pair, flow paths for viiow from one of said withdrawal devices to one oi said chambers and from the other chamber to one of said injection devices and, in an alternative half cycle, establishing, through the other two conduits, fio'w paths for ows from the other withdrawal device to lsaid other chamber and from said one chamber to the other injection device.

8. In a blood transfer apparatus, in combination with a pair of catheter means for insertion into blood channels of respective bodies, each of said catheter means including a withdrawal device and an injection device; a pair of metering chambers each having restricted passages communicating respectively with its upper and lower extremities; a pair of conduits branching from each of the lower passages and communicating with one each of said inlet and withdrawal catheter devices; means for inducing outflow from one of said chambers and inflow into the other of said chambers and, alternately, inducing inflow into said one chamber and outflow from said other chamber, said last means comprising a pair of pumping chambers communicating with the respective upper passages of said metering chambers, a pair of diaphragms each closing one side of a respective pumping chamber, an electric motor operated means for alternately moving one of said diaphragms inwardly while moving the other diaphragm outwardly and then moving said other diaphragm inwardly while moving said one diaphragm outwardly; and means responsive to change in blood level in said upper and lower passages respectively for directing said outows alternately to one and then the other of said injection catheters and for directing said inflows alternately from one and then from the other of said withdrawal catheters, said last means including solenoid operated valves having holding circuits, and limit switches actuated by said diaphragm operating means for opening said holding circuits periodically.

9. In a blood transfer apparatus, in combination with catheter means for insertion into blood channels of respective bodies, including a withdrawal device and an injection device; a pair of metering chambers each having restricted passages communicating respectively with its upper and lower extremities; a pair of conduits communicating respectively with said inlet and withdrawal catheter devices; means for inducing outflow from one of said chambers and inflow into the other of said chambers, and, alternately, for inducing inflow into said one chamber and outflow from said other chamber, said last means comprising pumps each having an inlet communicating with a respective withdrawal conduit and an outlet communicating with a respective injection conduit and also with a respective lower passage, a plenum chamber communicating with the upper passage of each of said metering chambers, a distensible diaphragm closing one side of each of said plenum chambers and adapted to be distended when blood is pumped into the respective metering chamber and to exert an evacuating pressure against said blood when the pumping action thereagainst is terminated, and means responsive to change in blood level in said upper and lower passages respectively for directing said outows alternately from one and then from the other of said withdrawal catheters.

10. In a blood transfer apparatus, in combination with two pairs of catheters for insertion into blood vessels of respective bodies: means defining a pair of metering chambers and a fluid connection for each chamber for conducting flows alternately into and out of the respective chamber; two pairs of uid conduits, each pair branching from a respective one of said connections and leading to respective catheters of each pair, the catheters of each body, being connected respectively to one conduit of each pair, and valve means arranged and automatically operable to render two of said conduits, consisting in one conduit of each pair, collectively operative in one half cycle of operation of the apparatus, to conduct flows from one catheter of one body to one of said chambers and from the other chamber to the other catheter of said one body, and to render the other two conduits collectively operative, in an alternate half cycle of operation, to conduct flows to and from the other two catheters, whereby to effect the transfer of a measured quantity of blood from one body to one of said metering chambers and the simultaneous transfer of a measured quantity of the blood of the other body from the other metering chamber to said one body.

11. In a blood transfer device, in combination with two pairs of catheters for insertion into the blood streams of donor and patient bodies respectively, including an injection catheter and a withdrawal catheter for each body: a system of flow conduits including a pair of conduits for each body, connected respectively to the inlet and Withdrawal catheters thereof; means defining a pair of metering chambers and a fluid passage for each chamber to function alternately as inlet and outlet therefor, each of said passages being connected to a conduit leading to the injection catheter of one body and to a conduit leading to the withdrawal catheter of the other body; a valve for each conduit, for controlling iiow therethrough; means for inducing fluid flows through said passages alternately into and out of the respective chambers, with fluid entering one chamber while fluid is leaving the other chamber, and vice versa; and means responsive to changes in the volumes of fluid in the respective chambers for opening the valves of one of said pairs of conduits and closing the valves of the other pair, in timed relation to the uid flows in said passages, such that the outflowing fluid from the chamber that is being emptied will flow to the injection catheter of one of the bodies, and the fluid flowing into the chamber that is being filled will come from the withdrawal catheter of the same body.

PETER F. SALISBURY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,170,958 Butler Feb. 8, 1916 1,531,698 Janes Mar. 31, 1925 1,696,496 McMurdo Dec. 25, 1923 1,886,818 Kipp Nov. 8, 1932 

